1. Technical Field
The present invention relates to an ink composition from which recorded matter having good fixability can be obtained on various recording media, in particular, non-water-absorbing or low water-absorbing recording media such as synthetic paper and printing paper.
2. Related Art
Ink jet recording is a printing technique for forming a print by ejecting ink droplets and making the ink droplets adhere to a recording medium such as paper. Due to recent innovative advancement in ink jet recording technologies, ink jet recording is being increasingly employed in the field of high-definition printing that has previously been realized by silver halide photos and off-set printing. With this advancement, inks for ink jet recording have been developed which can produce images having glossiness of silver halide photos by using highly glossy recording media, i.e., special paper, comparable to the developing paper, art paper, and the like that have been used in the fields of silver halide photos and off-set printing. Moreover, inks for ink jet recording that can achieve the image quality of silver halide photos even when plain paper is used have also been developed.
Due to recent widespread of image-forming technologies using digital data, desk top publishing (DTP) has become popular in the fields of printing in particular. Even when printing is performed through DTP, a proof for correcting color is produced beforehand to confirm the gloss and color of actual prints. Ink jet recording is being applied to outputting of such proofs. In DTP, the print needs to have high color reproducibility and high color stability; thus, special paper for ink jet recording is normally used as recording media.
Proof paper, which is special paper for ink jet recording, is prepared such that a print made therefrom has the same gloss and color as those of an actually output print on printing paper. As such, the quality and material for specialty paper are appropriately adjusted according to the type of printing paper but it increases the production cost to make specialty paper that is compatible to many types of printing paper. Thus, for color proof usage, it is desirable from the technical viewpoint if ink jet recording can be performed on printing paper rather than specialty paper. If samples made by performing ink jet recording directly on printing paper without using special paper can be used as the final proof samples, the cost for proofing can be dramatically saved. Moreover, synthetic paper prepared by mixing inorganic fillers and the like with polyethylene resins, polypropylene resins, or polyester resins and forming the resulting mixtures into films is widely used in the field of printing and is attracting attentions as environmentally friendly products that have high recyclability. Thus, it is desirable from the environmental viewpoint if recording can be conducted on such synthetic paper.
Printing paper is coated paper having a coating layer for receiving oil-based inks on its surface but has a low water-absorbing property. Thus, when water-based pigmented inks commonly used in ink jet recording are used, the inks exhibit low permeability into the recording medium (printing paper) and bleeding or coalescence may occur in the images.
To address the problem described above, for example, Japanese Unexamined Patent Application Publication No. 2005-194500 (Patent Document 1) discloses a pigment-based ink that reduces bleeding and exhibits excellent glossiness on special paper, in which a polysiloxane compound is used as a surfactant and an alkanediol such as 1,2-hexanediol is used as a dissolving aid. Japanese Unexamined Patent Application Publication No. 2003-213179 (Patent Document 2), Japanese Unexamined Patent Application Publication No. 2003-253167 (Patent Document 3), and Japanese Unexamined Patent Application Publication No. 2006-249429 (Patent Document 4) propose that high-quality images can be obtained by controlling the permeability of inks into recording media through addition of glycerin, a diol such as 1,3-butanediol, or a triol alcohol solvent such as pentanetriol to inks. However, ink compositions that can create recorded matter having higher fixability are still in pursuit.
Thermal printers are used in the on-demand label-printing market in which receipts, tickets, coupons, tags, labels, etc., are printed at the site and immediately provided to the end customers. However, printed matter created by thermal printers cannot always be used in the environment such as cargo rooms such as containers, where the printed matter is exposed to high temperatures or may undergo discoloration when left in a room temperature for a long time. Various improvements have been made on ink compositions for ink jet recording in order to obtain high-quality images. Further improvements are required in terms of fixability of ink in order for the ink compositions to be suitable for use in on-demand label-printing market.
In the on-demand label-printing market, frequently, the sites where printers are installed are sensitive to smell. Although use of highly volatile solvents is preferred for quick-drying, the solvents remaining on the paper may adversely affect the adhesives used in wallets, and substances and things such as wallets in contact with the printed matter when the printed matter was put in wallets or the like.